Configuring Regexp stack limits

[josh]

Hey @svaarala,

Hit an issue trying to get some code to compile within the CoffeeScript compiler within duktape (again, 😉).

I narrowed it down pretty far this time. And of course was Regexp related.

/^(?:[^\\"#]|\\[\s\S]|"(?!"")|\#(?!\{))*/.exec("form[data-remote] input[type=submit],\nform[data-remote] button[type=submit],\nform[data-remote] button:not([type]),\nform[data-remote-submit] input[type=submit],\nform[data-remote-submit] button[type=submit],\nform[data-remote-submit] button:not([type])\n\"\"\"")

duk> /^(?:[^\\"#]|\\[\s\S]|"(?!"")|\#(?!\{))*/.exec("form[data-remote] input[type=submit],\nform[data-remote] button[type=submit],\nform[data-remote] button:not([type]),\nform[data-remote-submit] input[type=submit],\nform[data-remote-submit] button[type=submit],\nform[data-remote-submit] button:not([type])\n\"\"\"")
RangeError: regexp executor recursion limit
    duk_regexp_executor.c:145
    exec  native strict preventsyield
    global input:1 preventsyield

It seemed like this specific example was just a few iterations over the 1000 deep stack limit for DUK_RE_EXECUTE_RECURSION_LIMIT. I only had to bump it up to 1006 and it started working.

Do you think this default limit is to small for the deep stack mode? Or is this something we can make easier to configure via a compile time flag?

Thanks!

[svaarala]

It should be easy to make configurable - I can address it as part of #64 for example.

Probably the better fix would be to make the Regexp engine pluggable (#74). The built-in engine is a pretty minimal implementation because of footprint restrictions, and does backtracking through the C stack which is a limiting factor for large inputs.

[svaarala]

Bumped regexp stack depth from 1000 to 10000 for the 1.2.0 release.

In 1.3.0 this should be addressed by adding a DUK_USE_xxx option for the stack limits so that they're configurable from duk_config.h (one can then e.g. use sed/awk/patch to replace values).

[josh]

Works for me, thanks again @svaarala!

[svaarala]

The 1.3.0 DUK_USE_xxx issue is tracked as #165.